The free search option enables the researcher to search for any text (any word, any string of characters). You can also use numbers to find documents in a specific year.
Note: To avoid a crash of your computer due to the large number of descriptions, you have to use at least four characters.
Note: When you use more than one word, each separated by a space, you will get less search results. Using more than one word means that you will find descriptions of documents that contain all of these words (xxx and yyy and zzz).